The first puzzle is how he will fit into the team, because there is no simple solution for Carlo Ancelotti. Whatever decision he makes will have knock-on effects for the rest of the side.

I rate Torres highly. He certainly will bring greater goal threat to Chelsea, but Ancelotti needs to integrate him into the side without causing too much disruption. His arrival surely signifies a change of role for Didier Drogba. For the past seven seasons he has been the main striker, the man around whom the others had to play. His 37 goals last season were a major reason Chelsea were able to win both the Premier League and the FA Cup.

CHANGE

But the club's owner, Roman Abramovich, has not spent £50m to see Torres sitting on the bench. So either Drogba has to accept that his role in the team is going to fundamentally change, or he will be dropped.

The ideal scenario for Ancelotti is probably finding a way to play both Torres and Drogba together, because they are potentially a devastating partnership.

The clearest indication of his thinking came in midweek, when he tinkered with his formation, even though Torres was not part of the team that won 4-2 at Sunderland.

Some thought Nicolas Anelka would be dropped to make way for Torres, but at the Stadium of Light the Frenchman played a deeper role behind a front two of Drogba and Salomon Kalou. If you take out Kalou and put in Torres, then you have a possible formation to face Liverpool.

That works for me. Anelka certainly has the ability to play that role. It probably suits him a bit better now than it might have done earlier in his career. He is a talented player and can see a pass. By all accounts he seems to have thrived in the role at Sunderland, and I can see Ancelotti wanting to give it another go against Liverpool tomorrow.

The big advantage of that system is that it allows you to play both Drogba and Torres. Other than going with a midfield diamond, a system which was used last season, but discarded, I can't see another way of fitting both of them in.

The drawback is that it leaves you lacking natural width. I can't see Frank Lampard and Michael Essien bombing down the flanks to provide the ammunition for Drogba and Torres, so it means you are relying on your full-backs to get up the pitch.

The good thing for Chelsea is that they have been asking their full-backs to do that for some time now. They are always looking for a chance to get forward.

The alternative is to play with pretty much the same 4-3-3 system that was used when they won the 'double' last season. It would mean less tactical disruption to the rest of the team, but it would mean leaving Drogba out. That is the problem for Drogba -- he cannot play out wide, or play a different kind of role. And if it doesn't work with Torres, then he will be the one to miss out.

Anelka, in contrast, is more adaptable and can play in a variety of roles in the Chelsea attack. He has played as a target man, or out wide, or in the deeper role he adopted in midweek. Drogba is not so flexible.

I will be fascinated to see Torres tomorrow. He clearly had his head turned by Chelsea, and this season he has appeared to be sulking and not produced too many performances for Liverpool. I think Torres has let Liverpool down this season, but now he has got the move he wants we should see a motivated player who is keen to prove a point.

Accommodating him in the Chelsea team may not be all that easy, and Ancelotti does not have much time to change things around. That's one of the reasons Arsene Wenger doesn't like buying in the January window, because you don't have time for the new players to bed in.